This invention relates in general to vehicle wheels and, in particular, to an improved vehicle wheel cover-retention system and method for producing the same.
Automotive wheels serve two main purposes: the wheels support the vehicle and associated tires and the wheels provide an aesthetically pleasing appearance. Current technology often involves tradeoffs between those two goals. Wheels are typically constructed of metal or metal alloys, although alternative materials, such as composites, are envisioned. The aesthetic appearance of such a wheel is limited by manufacturing methods to form a given styled surface. Additionally, such a wheel will often have excess material (and weight) added to form the styled surface.
Wheel clads or covers are used to simulate a styled wheel surface while utilizing a structural wheel underneath to support any loads imparted on the wheel. The wheel cover is typically made of a plastic or thin metal material that is more easily formable into pleasing aesthetic shapes. The cover is then attached to the wheel by mechanical means, whether fasteners, adhesives or locking features formed into the cover or the wheel. The cover can also receive a special surface coating to enhance its appearance, such as a bright paint or chrome plating. It is desirable that the cover is not easily discernible as separate from the wheel. It is also desirable to eliminate evidence of a cover being used such as mating lines, a hollow sound when tapped, yielding to moderate pressure, preventing the entry of foreign matter between the parts and visible wheel surfaces behind the cover. To this end, a suitable adhesive foam material is often used to deaden the hollow sound when tapped, fill the space between the wheel and cover to prevent entry of foreign matter and support the cover when pressure is applied to the cover.
It can be very difficult to use adhesives to join the cover and the wheel in a high volume manufacturing environment because the adhesive requires sufficient time for a chemical reaction to occur and expand (in the case of foam adhesives), attain handling strength and subsequently full strength. A fast curing adhesive will allow faster throughput but also cures quickly in the mixing equipment and requires more maintenance. Conversely, a slow curing adhesive possesses a longer open time before clogging inside the dispensing equipment but requires more work-in-process inventory and related resources, such as, floor space, cure ovens, material handling equipment and tooling.
Furthermore, when using an expanding foam adhesive material, the cover and wheel assembly can be encapsulated inside a masking mold to contain the expanding foam adhesive material. However, there often exists a path internal to the cover and wheel assembly through which it is undesirable to allow the expanding foam adhesive material to enter. It is not feasible to mask off certain areas when the cover and wheel are assembled.